Model Aviation $250 Racing Quad Challenge

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Multirotor racing continues to grow in popularity, and has accounted for the largest number of new AMA members in 2017. Although you can purchase a complete, ready-to-fly FPV racing quadcopter, most are built by their pilots. Building your own quad allows you to use the components you want and makes upgrades and repairs easier, thanks to the knowledge you gained during the build.

If you have decided to build your own FPV racing quad, you’ll have many choices when it comes to components. Three AMA employees, Matt Ruddick, Dillon Carpenter, and Kyle Jaracz, took on that task with an added requirement. They were not to spend more than $250 for everything except the transmitter and receiver. Our three participants would then compete against one another to determine the Model Aviation Racing Quad Challenge Champion.

In this article, you will learn about their builds, including the types of components and why they selected them. After you have read the article, check out the video of the competition and learn more about the competitors and their quads.

The Build Components

Matt

Dillon

Kyle

Frame

Space One Meteor 5-inch X

Space One Meteor 5 inch

X Valorem

Flight Controller

RaceFlight Revolt FC

CL Racing F4

Flip 32 F3

ESC

Siskin 31A Four-in-One

Siskin 31A Four-in-One

Hobbywing XRotor 40-amp

Motors

RMRC Silver Line

Emax 2205 2,600 Kv

RCX H2208 2205 2,600 1,800 Kv

VTX

TBS Unify Pro Race HV

TBS Unify Pro Race HV

Eachine VTX03 Super Mini

Antenna

Pyro-Drone 5G8 Linear

Spedix Pagoda

Included Dipole

Camera

Foxeer HS1177

Foxeer Arrow Micro

RunCam Swift Mini

Battery

RMRC Orange Series 4S

CNHL 4S 70C

Tattu R-Line 6S 70C 1,300 mAh 95C

Propellers

Dalprop Cyclone 5050C

Gemfan Flash 5051

Gemfan 5152

Misc. Hardware

Anti-Vibration Standoff

None

Capacitor & RMRC Mini PDB

Total Cost

$248.90

$249.93

$235.01

Matt Ruddick

For my build, I had one goal in mind: Keep it simple. I wanted to make sure that I found tried and tested components that I knew would work out of the box and give me a reliable system with which to work. In my opinion, the most important components would be the flight controller and the ESCs.

Of course, these components would normally be the most expensive parts of a build, so I knew that most of my budget would land there. For the flight controller, I chose the RaceFlight Revolt. This is my flight controller of choice on other builds, so I knew that I would be working with a quality component.

I also knew that I’d have few surprises when it came to setting up and handling the quad. After it is set up, the Revolt never fails to give me a “locked-in” feeling right out of the box, with little or no need for tuning.

I decided to use a four-in-one ESC to take advantage of the smaller frame. Although I haven’t used this component before, I chose the Siskin 31-amp four-in-one ESC based on recommendations from other pilots. I was confident that I’d have little trouble integrating it into this build.

I knew I wanted to go with a motor that had a relatively high Kv rating, but I didn’t want to break the bank. In fact, I couldn’t! Luckily for me, Ready Made RC (RMRC) has just released a new series of motors called the RMRC Silver Line. At slightly less than $11 per motor, these 2205 2,600 Kv silver beauties were perfect for the setup I wanted—no frills and straight speed. They came with extra-long motor wires that would match up well with the four-in-one ESC I planned to use. They also featured a hollow shaft and offered approximately 850 grams of thrust.

I matched those motors with 5050C Cyclone propellers from Dalprop. I normally fly three-blade propellers, but I really saw this as one of my secret weapons. I knew that my competitors would likely spend extra money on a set of two-blade propellers for our speed challenge and a set of three-blade propellers for the race. I decided to save a few dollars and just purchase a single set of two-blade propellers. I knew that for my racing ability level, I would likely never utilize the advantages of a three-blade propeller.

There are two major video transmitter (VTX) players on the market: TBS and its Unify VTX, and Immersion RC’s Tramp HV. You can’t go wrong with either product, but when I looked at my budget, I went with the Unify Race edition. It was $20 less than the Tramp HV, although it offered less in terms of features. I found it had everything I needed in a VTX, however, and I knew I could rely on it to work each time I powered up.

As for matching an antenna to the Unify, I used this as a place to save a little more money. I went with a linear polarized whip antenna from Pyro-Drone that was less than $5. If you’re merely flying at a local club field with a friend, this antenna will work great for you. It is super durable and at that price, you can have spares on hand, just in case!

There are many FPV camera options available, and they all come with features that can be attractive to any pilot. For the purposes of my build and its theme of keeping it simple, I chose the trusty Foxeer HS1177.

Finally, all of these components needed a frame upon which to live. There aren’t many options for budget-friendly frames out there that aren’t clones of existing products; however, there is a manufacturer based in California that designed my first quad’s frame more than a year ago that offers an inexpensive option.

Space One FPV’s Meteor 5-inch frame for $24.95 is a true X-frame designed for both beginners and advanced pilots. It offers plenty of space for your stack and is rock solid after it is constructed.

My only complaint about the Meteor is that the camera mount sticks out far enough that some propellers will clip it. I did not have that problem with my propeller choice; however, they didn’t miss it by much. That mount would likely need to be modified in some situations.

Dillon Carpenter

Building a budget racing quad for $250 is a task that, at first, sounded daunting. It’s easy to get caught up in the hype of the latest and greatest technology that is being released fairly consistently and forget about the tried-and-true equipment of years, months, and even weeks past. This challenge has provided a filter for my own nearsightedness in the market because I found out that I could build a capable and quick racing multirotor with a manageable $250 budget.

I focused primarily on the powertrain for the build and worked out which motors, battery, propellers, and ESCs were a priority, and then made the rest of the build fit into the budget. Motors are usually the biggest investment, with some premium motors retailing for as much as $20 or $25 each. I went with Emax RS 2205 2,600 Kv motors, or “O.G. Redbottoms” as they’re affectionately called in the multirotor community.

I decided to go with a higher Kv rating to be able to get more rpm out of my propellers because I was planning to use the relatively high-pitched Gemfan Flash 5152 two-blade propellers. These allow for an extra bit of thrust potential to aid in the top speed test, with the sacrifice of some stability and handling compared with a three-blade propeller.

In my experience, China Hobby Line (CNHL) 1,300 mAh 100C 4S LiPo batteries have an excellent cost-to-performance ratio, especially considering that they are only $19. I went with the reasonably priced Siskin 31-amp four-in-one ESC for $49 to save space and weight on the build.

The CL Racing F4 flight controller has all of the features I expect in a racing quad. With built-in Betaflight On-Screen Display (OSD), an F4 processor, built-in power distribution board, and current monitoring, this flight controller is a no-brainer for $30. The flight controller and the ESC came with ports to connect them, which made for an easier build. I also used a set of rubber standoffs for the flight controller to isolate any vibrations that might make it to the gyro.

I was able to get a decent FPV system with the remaining budget. The Foxeer Arrow Micro is the company’s new micro-size camera. Weighing 5.5 grams, this camera saved weight compared with using a traditional FPV camera. The Team BlackSheep (TBS) Unify Pro Race version features Smart Audio, which, when paired with Betaflight OSD, allows a pilot to change video channels, bands, and power output with his or her transmitter through the OSD in the goggles.

I’m impressed by Maarten Baert’s pagoda antenna design and used a fairly inexpensive thermoplastic polyurethane-reinforced Spedix Pagoda II antenna. The frame that all of these components were packed into was the Space One FPV Meteor 5-inch frame. Had I known about the design flaw that didn’t allow the propellers to clear the included camera mount, which required some modification, I would have gone with another frame.

Coming in barely under budget at $249.93, the only thing I wasn’t able to fit in was a $1.50 capacitor to protect my electronics and clean up
any electrical noise.

Overall, I was impressed with how well the quadcopter turned out. It is quick, handles well, is fairly simple to build, and uses components from reputable manufacturers and US-based vendors. I would definitely recommend this build to anyone looking to get into FPV racing at a reasonable cost.

Kyle Jaracz

When Model Aviation Editor-in-Chief Jay Smith presented this challenge, I was excited to get started. As I began to compile a parts list, I thought of another challenge. What if I went with a 6S LiPo battery as the power source?

Because I had never built anything other than 4S quads, the challenge to find appropriate electronics and hardware that could handle that amount of power was definitely intriguing. Besides, what better way to add some excitement to the competition and for you, the viewer, than offering a different option? Oh, and if I failed spectacularly, there would likely be some exciting footage!

After deciding to use 6S power, my parts list began to take on an entirely different shape. Finding a frame was the easy part. I had a chance to look over the RMRC Valorem frame while I was at the Willard, Ohio, FPV Fest last summer. I had been impressed by the build quality and the frame’s price point. Also in its favor, RMRC offers many variations of arm options. Whatever your favorite setup is, the Valorem is a strong, budget-friendly contender.

Lacking experience with “what works” using 6S power, choosing a motor was more difficult. I needed something with a relatively low Kv and larger diameter and height to handle the extra power. I stumbled upon the website MyRCMart.com that had 2208 1,800 Kv powerhouses. The price couldn’t be beat and I was able to fit five motors into the budget—always a good thing to have a spare on hand for mishaps.

I chose the Hobbywing XRotor ESCs in 40-amp capacity. In hindsight, I could have gotten away with a 35-amp unit, and I wish that I had gone with something more current.

The Hobbywing ESCs communicate with the flight controller via Pulse Wave Modulation. This is an older method of communication between the flight controller and the ESC. This provides a low refresh rate, creating a significant wobble at full throttle and limits the quad’s top speed and controllability. The ESCs might be able to be updated with new software (which I will attempt after the competition is complete), but I didn’t feel that this was in keeping with the challenge’s theme.

The Flip 32 flight controller has flown just fine. I had a few issues in getting the board to flash with the latest software using Betaflight 3.2, and ended up going to several others for advice before we got it to flash. Since then it has been working well. A more costly component might have saved some heartache, but in all, it was a solid choice.

I saved some money on the VTX by going with the Eachine. Although I was initially leery of this VTX, I’ve had great reception and it is easy to change both frequency and output on the unit. I miss the ability to switch out antennae and polarization. I paired the VTX with the RunCam Swift Mini and I’ve had no issues.

I went through several propeller options before I decided on the Gemfan 5152 series. I chose two-blade propellers for the speed runs and three-blade ones for the race. I couldn’t be happier with their performance and durability.

It’s important to note that with all of the blades I tested, I made sure to check the temperatures of the components as I progressively pushed the quad. I never got to the point where I was concerned with anything getting too warm. To the contrary, the combination I put together for this build was typically only warm at the end of a pack, and then only if it was really being pushed.

As I finished the build, I began to think of what I should name this particular quad. I don’t normally give such consideration, but this was a special sort of build. I decided to dig into my RC roots, having been taught to name each sailplane I built long ago by my mentor, Pete Peterson, who used Norse mythology to name his aircraft.

I decided upon the Norse god of war and the upholder of justice, Tyr. This also made sense because my racing handle is “Blucord,” an homage to my infantry days. Of course, students of mythology will recall that this particular god is missing a hand. It turned out that this was prophetic, but you’ll have to check out the video to see what actually happened.

In summary, I’m happy with the build. I enjoyed stretching my comfort level and building something new. Having 6S power in the flights is exhilarating! If you’ve not built a 6S multirotor, think about trying one for your budget build. Be sure to write and let me know how it goes!